scholarly journals Anaerobic Nitrogen Turnover by Sinking Diatom Aggregates at Varying Ambient Oxygen Levels

2016 ◽  
Vol 7 ◽  
Author(s):  
Peter Stief ◽  
Anja Kamp ◽  
Bo Thamdrup ◽  
Ronnie N. Glud
Keyword(s):  
Oxygen Levels ◽  
Nitrogen Turnover ◽  
Ambient Oxygen

scholarly journals Low Oxygen Delays Budbreak of Apple Trees in Greenhouse and Prolongs Storage Life

HortScience ◽  
1991 ◽  
Vol 26 (7) ◽  
pp. 890-891
Author(s):  
Eric Young ◽  
S.M. Blankenship
Keyword(s):  
Malus Domestica ◽  
Shoot Growth ◽  
Storage Life ◽  
Low Oxygen ◽  
Apple Trees ◽  
Bud Development ◽  
Oxygen Levels ◽  
Ambient Oxygen

Three percent oxygen significantly delayed and reduced budbreak of fully chilled apple (Malus domestica Borkh.) trees in a greenhouse. When ambient oxygen levels were restored, budbreak occurred normally. Apple trees stored under 3% ± 1% oxygen at 6C for 35 weeks had no detectable bud development in storage. Budbreak and subsequent shoot growth were normal after the trees had been removed from storage.

Elevated ambient oxygen does not affect autoregulation in cat mesentery

1988 ◽  
Vol 255 (1) ◽  
pp. H131-H137 ◽  
Author(s):  
D. J. Lang ◽  
P. C. Johnson
Keyword(s):  
Blood Flow ◽  
Abdominal Cavity ◽  
Tissue Oxygen ◽  
Oxygen Levels ◽  
Cell Velocity ◽  
Ambient Oxygen ◽  
Significant Difference ◽  
Red Cell Velocity ◽  
The Mean ◽  
Control State

The purpose of this study was to determine whether oxygen plays a role in the autoregulation of blood flow in the isolated mesentery of the cat. Arteriolar diameter and red cell velocity were measured at normal arterial pressure and during 2 min of pressure reduction to 80 and 40 mmHg under ambient levels of 0, 10, and 20% oxygen in nitrogen. Autoregulatory responses during pressure reductions to 80 and 40 mmHg were not significantly different under 0% oxygen compared with those under 10 or 20% oxygen. Also, no significant difference was found in the control state between the mean diameters, linear velocities, or volume flows under 10 and 20% oxygen compared with 0% oxygen. We also determined oxygen levels just under the mesentery with different ambient oxygen levels. These values were the same as in the ambient gas mixture, suggesting that tissue oxygen levels in mesentery are determined by those in the external environment. Oxygen levels in the abdominal cavity averaged 67 mmHg, indicating that mesentery is normally exposed to a high-oxygen environment. We conclude that a change in tissue oxygen tension is not an essential factor in the mechanism of blood flow autoregulation in cat mesentery.

scholarly journals Measurement of Predation and Biofilm Formation under Different Ambient Oxygen Conditions Using a Simple Gasbag-Based System

2013 ◽  
Vol 79 (17) ◽  
pp. 5264-5271 ◽  
Author(s):  
Daniel E. Kadouri ◽  
Aimy Tran
Keyword(s):  
Positive Association ◽  
Predatory Behavior ◽  
Low Oxygen ◽  
Gram Negative ◽  
Content Type ◽  
Current Configuration ◽  
Oxygen Levels ◽  
Ambient Oxygen ◽  
Predatory Bacteria ◽  
Biofilm Development

ABSTRACTBdellovibrio bacteriovorusandMicavibrio aeruginosavorusare Gram-negative bacteria characterized by predatory behavior. The aim of this study was to evaluate the ability of the predators to prey in different oxygen environments. When placed on an orbital shaker, a positive association between the rate of aeration and predation was observed. To further examine the effects of elevated ambient oxygen levels on predation, a simple gasbag system was developed. Using the system, we were able to conduct experiments at ambient oxygen levels of 3% to 86%. When placed in gasbags and inflated with air, 50% O2, and 100% O2, positive predation was seen on both planktonic and biofilm-grown prey cells. However, in low-oxygen environments, predatory bacteria were able to attack only prey cells grown as biofilms. To further evaluate the gasbag system, biofilm development of Gram-positive and Gram-negative microorganisms was also measured. Although the gasbag system was found to be suitable for culturing bacteria that require a low-oxygen environment, it was not capable of supporting, with its current configuration, the growth of obligate anaerobes in liquid or agar medium.

Influence of Decreased Ambient Oxygen on Susceptibility of Rats to Audiogenic Seizures

1956 ◽  
Vol 187 (3) ◽  
pp. 571-572
Author(s):  
Walter G. Mitchell ◽  
Fred A. Hitchcock
Keyword(s):  
Wistar Rats ◽  
Audiogenic Seizures ◽  
Audiogenic Seizure ◽  
Seizure Susceptibility ◽  
Excitatory Effect ◽  
Oxygen Levels ◽  
Ambient Oxygen ◽  
Biphasic Effect ◽  
Male Wistar Rats ◽  
Effect Of Oxygen

Male Wistar rats were tested for audiogenic seizure susceptibility at various levels of decreased ambient oxygen. At 15.9% and 12.3% oxygen, the number of seizures occurring were approximately the same as the controls. Enhancement of seizure susceptibility occurred at 14.5% ambient oxygen, indicating a preliminary excitatory effect. Oxygen levels of 9.6% and below resulted in inhibition of seizures. The over-all picture was that of a biphasic effect of oxygen lack on audiogenic seizure susceptibility.

Letter to the Editor

PEDIATRICS ◽  
1969 ◽  
Vol 43 (4) ◽  
pp. 638-639
Author(s):  
John H. Knelson ◽  
Mary Ellen Avery
Keyword(s):  
Partial Pressure ◽  
Oxygen Tension ◽  
Newborn Infants ◽  
Capillary Blood ◽  
Partial Pressure Of Oxygen ◽  
Oxygen Levels ◽  
Arterial Blood ◽  
Letter To The Editor ◽  
Ambient Oxygen

The letter from Drs. Stefan, Leschin, and Gray raises the important question of the validity of measurements of the partial pressure of oxygen (PO2) in capillary blood. We concur that measurements of oxygen tension are essential in monitoring ambient oxygen levels, and we would agree that, in the absence of shock, values on capillary blood reflect the levels in arterial blood. Fortunately, data exist, at least in normal newborn infants breathing air, that permit evaluation of the usefulness of capillary samples.

scholarly journals Oxygen limitation is not the cause of death during lethal heat exposure in an insect

2019 ◽  
Vol 15 (1) ◽  
pp. 20180701 ◽  
Author(s):  
Philipp Lehmann ◽  
Marion Javal ◽  
John S. Terblanche
Keyword(s):  
Thermal Tolerance ◽  
High Performance ◽  
Tissue Oxygenation ◽  
Heat Exposure ◽  
Pieris Napi ◽  
Oxygen Levels ◽  
Thermal Limits ◽  
Ambient Oxygen ◽  
Wide Range ◽  
Internal Body

Oxygen- and capacity-limited thermal tolerance (OCLTT) is a controversial hypothesis claiming to explain variation in, and mechanistically determine, animal thermal limits. The lack of support from Insecta is typically argued to be a consequence of their high-performance respiratory systems. However, no studies have reported internal body oxygen levels during thermal ramping so it is unclear if changes in ambient gas are partially or fully offset by a compensatory respiratory system. Here we provide such an assessment by simultaneously recording haemolymph oxygen (pO 2 ) levels—as an approximation of tissue oxygenation—while experimentally manipulating ambient oxygen and subjecting organisms to thermal extremes in a series of thermolimit respirometry experiments using pupae of the butterfly Pieris napi . The main results are that while P. napi undergo large changes in haemolymph pO 2 that are positively correlated with experimental oxygen levels, haemolymph pO 2 is similar pre- and post-death during thermal assays. OCLTT predicts that reduction in body oxygen level should lead to a reduction in CTmax. Despite finding the former, there was no change in CTmax across a wide range of body oxygen levels. Thus, we argue that oxygen availability is not a functional determinant of the upper thermal limits in pupae of P. napi .

scholarly journals A many-to-one sensory circuit encodes oxygen levels and drives respiratory behaviour in Danio rerio

2019 ◽  
Author(s):  
Chen-Min Yeh ◽  
Gerald M. Pao ◽  
Reginno Villa-Real ◽  
Kaila Rosales ◽  
Elizabeth DePasquale ◽  
...  
Keyword(s):  
Sensory Neurons ◽  
Danio Rerio ◽  
Respiratory Activity ◽  
Oxygen Sensing ◽  
Neural Circuitry ◽  
Neuroendocrine Cells ◽  
Purinergic Signalling ◽  
Sensory Coding ◽  
Oxygen Levels ◽  
Ambient Oxygen

AbstractIn most animals, respiratory activity inversely correlates with environmental oxygen levels1,2. However, less is known about how the underlying neural circuitry encodes oxygen information and modifies behaviours. Here, we characterize the oxygen sensing circuit and reveal sensory coding principles in a Danio rerio larva, an optically accessible vertebrate that increases respiration and startle-related responses under hypoxia3. We observe that cranial sensory neurons receive input from multiple oxygen-sensing neuroendocrine cells, and then relay this information to hindbrain targets. Moreover, hypoxia evoked increase in cranial sensory dendrite calcium events indicates an oxygen-driven change in input dimensionality, which is also represented in their cytoplasm. Additionally, we estimate that a neural code using cytoplasmic calcium events requires most of the cranial sensory neurons, whereas one integrating input dimensionality needs only a third. Furthermore, we show that purinergic signalling at the neuroendocrine cell-sensory neuron synapses drives hypoxia-induced respiratory changes, independent of serotonin, which triggers startle-related responses. Collectively we demonstrate that oxygen coding employs a “many-to-one” sensory circuit that transforms ambient oxygen into neuronal activity and input dimensionality changes to impact behaviour. More broadly, we suggest that multi-dimensional coding might be a common feature of many-to-one circuit motifs, revealing a function for related circuits across species.

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